Attempts have previously been made to plant seeds or seedlings by dropping containers which contain the seeds or seedlings from an aircraft. The planting containers may bear fins for aerodynamic stability and a pointed nose for penetrating the soil and also may have wall portions penetratable by the roots of the seedling; the containers may be dropped by low altitude aircraft such as helicopters. U.S. Pat. No. 3,755,962 issuing Sept. 4, 1973, to John Walters et al. and entitled "Aerial Planting Method and Apparatus" discloses one form of an air drop planting system incorporating the features mentioned above.
Such planting devices constitute a hollow containers, the interiors of which are provided with a suitable growing medium; because of the aerodynamic design of the containers, and due to the influence of gravity, the containers fall nose first, and penetrate the soil to plant the seed or seedling.
Further, attempts have been made to incorporate within such airborne planting device means to promote growth. In U.S. Pat. No. 3,273,284 issuing Sept. 20, 1966, to G. N. Anagnostou and entitled "Planting Container", a container is provided which is made of a material which disintegrates upon exposure to water and is formed in part from fertilizers and pulp, with the lower end of the receptacle being weighted with iron pellets to assure nose first air drop. A water filled membrane is provided to cushion the root system of the tree seedling and to supplement the natural water supply. Thus, the planting container of the latter patent is employed in a fed versus a non-fed transplant device which distinguishes this device from that of U.S. Pat. No. 3,755,962.
Applicant has determined that the planting container of Anagnostou, while constituting an important element in a fed transplant system, is not the complete solution to the problem, since most foresters have learned to avoid conventional water soluble starter fertilizers because of the inherent danger to seedlings. The risk of burning roots is great; measuring and mixing the conventional water soluble starter fertilizers with the soil is time consuming and the effects are short lived.
Most all replanting projects are usually on cutover timber land, land strip mined for coal or oil shale, abandoned row crop or pasture land, etc. On such soils, transplants must struggle for years until (and if) they can crowd out the vigorous brush and weeds which compete with them for water, sun and plant nutrients. One or more spot replantings are par for the course to replace the seedlings that never took or which were overwhelmed by weeds or brush.
In the field of land reclamation, seedling trees face an unfavorable, even hostile environment. Soil is often so coarse that suitable fertilizers leach away before the plants get much good from them or the soil is so acid or alkaline that soil chemicals fix (lock up) nutrients in forms that are unfavorable for planting. Land reclamation crews are understandably reluctant to carry around heavy bags of granular fertilizer and measure and mix it with backfill in the normal transplanting process due to the weight of the fertilizer and the nuisance in dealing with it.
There has been developed an organic nitrogen fertilizer which is acted upon by soil bacteria to provide timed release of the approximately 38 percent total nitrogen content of that fertilizer, of which from about 24-28 percent is water insoluble and the balance is soluble only in large amounts of water. This organic nitrogen fertilizer, known as ureaform, is commercially available under the registered trademark NITROFORM by Boots Hercules Agrochemicals Company of Wilmington, Del. The ureaform is composed of a series of low solubility and water-insoluble carbon-nitrogen units known as methyleneureas and is achieved by the reaction of formaldehyde with urea under controlled conditions and in prescribed proportion. Under reaction, a complex of methyleneurea molecules of varying molecular weight are produced. The commercial product, which is available in either a fine powder or particulate form, permits nitrogen release by soil bacteria similar to that occurring from natural organic fertilizers. Bacteria initially acts to release available nitrogen by breaking down the more soluble shorter chain, low molecular weight molecules over a relatively short period of four to six weeks, depending upon soil temperature. Within the ureaform, the intermediate-length methyleneurea molecules being soluble in hot water only, require more time for conversion to available nitrogen, for instance, over six months of the growing season. The longer chain molecules are insoluble in hot water and are more slowly converted. Thus, the ureaform constitutes a soil bacteria degradable polymeric material which makes nitrogen available in a controlled release fashion.
It is, therefore, a primary object of the present invention to provide an improved air drop planting system and planting device for the same in which the air drop planting device bearing a seed or seedling incorporates within the device body nutrients for supporting plant growth over an extended period of time whose release is responsive to soil bacteria action, which body material is non-water soluble, and in which the risk of root burning is eliminated.
It is a further object of the present invention to provide an improved air drop planting system and planting device in which a hollow cone body is formed of a soil bacteria degradable pressed powder material including a localized zone bearing nutrients and surrounding the area of the side roots of the internally carried plant.
It is a further object of the present invention to provide an improved air drop planting device in which the compounding of the hollow cone body material, the growing medium density, the nose cone construction, the roughness of the outer surface of the body and its center of gravity combine to achieve necessary aerodynamic stability of the air drop planting device, without requiring added stability structure to the hollow cone body.
Another object is to provide an air drop planting device and process whereby the seed or seedling container is especially designed to penetrate the soil due to the influence of the down draft of the propeller of the aircraft from which the container is dropped.